The present invention relates to filler tubes for fuel tanks for motor vehicles and more particularly to the closure for the refueling nozzle receiving end of the filler tube or neck as it is commonly referred to.
Recent mandated requirements for limiting fuel vapor emission to the atmosphere from motor vehicle fuel tanks and fuel supply systems have required an on-board diagnostic system which monitors the integrity of the fuel system at selected intervals during operation to determine if vapor leaks are present in the system. Typically, such on-board diagnostics utilize electrically controlled valves in the vapor vent lines to permit the engine air inlet or induction system to draw a slight vacuum in the system and measure the leak rate of the system as a function of the change in the vacuum over a selected time interval. Alternatively a slight positive or gage pressure may be employed to detect leakage. Currently, production motor vehicles are equipped with an on-board diagnostic system which performs such vacuum or pressure leak tests periodically during operation of the vehicle automatically without any knowledge of the vehicle operator. However, if a fault is detected in the system, an indicator for the operator is energized.
In systems employing a vacuum for leak testing, in order for such on-board diagnostic systems to be effective in drawing a vacuum in the fuel system including the tank, the filler cap on the tank filler neck must be adequately sealed in order to create the vacuum in the tank. Inasmuch as fuel tank filler caps are removed and repositioned many times by the vehicle operator over the service life of the vehicle, the filler cap has proven to be a source of trouble and often leakage due to wear or improper positioning by the vehicle operator; and, thus the on-board diagnostic system will indicate a fault in the integrity of the vapor containment in the fuel system. Thus, it has been desired to eliminate the filler cap for the fuel tank filler neck and to provide a way or means for permitting the vehicle operator to engage a refueling discharge nozzle with the filler neck and to provide for automatic closure and sealing of the filler neck upon removal of the nozzle without utilizing a removable filler cap.
Providing an automatic capless sealing closure for a fuel tank filler neck has proven to be a real challenge inasmuch as the closure must withstand not only the inertial loads imposed by vehicle bounce and jounce, but must also maintain the integrity of the filler neck closure seal in the event of a collision and/or vehicle rollover.
Thus, it has long been desired to provide a capless closure for a vehicle fuel tank filler neck which provides for a positive seal which can be maintained during the on-board diagnostic vacuum or pressure leak test and which can be latched to ensure that the closure and seal are maintained during collision and/or rollover in a manner which is easy to install on the vehicle, user friendly for refueling operations and which is low in cost to facilitate use of the mechanism or device in high volume production.